Castor assembly

ABSTRACT

A swivel castor assembly comprising a bracket, a castor rotatably mounted in the bracket, a plate member for securing the castor assembly to the structure, a bearing assembly between said plate member and bracket to facilitate rotational movement of said bracket relative to said plate member, said bearing assembly comprising inner and outer rings spaced apart to define an annular space between said rings having confronting circumferentially extending raceways, a plurality of rolling elements in the space between said rings, one of said rings secured to said bracket and the other of said rings secured to said plate member, means defining an access opening in said inner ring to permit assembly of the rolling elements, said access opening extending perpendicularly to a plane in which a couple is active due to load on the bearing in the area of least load relative to the load applied to the castor assembly.

United States Patent Asberg et a1.

[451 Aug. 22, 1972 [54] CASTOR ASSEMBLY [72] Inventors: Sture Asberg, Lilla Pukevagen 5, Savedalen, Sweden; Hendrikus Jacobus Maria 'limmer, lrenelaan 39, Ede, Netherlands [22] Filed: Dec. 17, 1970 [21] Appl. N0.: 99,042

Related US. Application Data [62] Division of Ser. No. 807,545, March 17, 1969,

Pat. No. 3,606,503.

[30] Foreign Application Priority Data Nov. 14, 1968 Netherlands ..6816232 Nov. 14, 1968 Netherlands ..6816233 [52] US. Cl ..l6/20 [51] Int. Cl. ..B60b 33/00 [58] Field of Search ..l6/20, 21,22, 23, 24, 25,

Primary Examiner-Bobby R. Gay Assistant Examiner-Doris L. Troutman Att0rney-Howson and Howson ABSTRACT A swivel castor assembly comprising a bracket, a castor rotatably mounted in the bracket, a plate member for securing the castor assembly to the structure, a bearing assembly between said plate member and bracket to facilitate rotational movement of said bracket relative to said plate member, said bearing assembly comprising inner and outer rings spaced apart to define an annular space between said rings having confronting circumferentially extending raceways, a

[56] References Cited castor assembly.

UNlTED STATES PATENTS 3 Claims, 3 Drawing Figures 757,824 4/1904 Martin .;...16/21 3,224,032 12/1965 McLean ..l6/26 1,421,626 7/1922 Warnock 16/21 PATENTEnwszz m2 3.685090 srum: Assam HENDRIKUS JACOBUS MARIA TIMMER ATTORNEYS CASTOR ASSEMBLY This is a Divisional application of our prior copending application, Ser. No. 807,545 filed Mar. 17, 1969, entitled Rolling Bearing, now US. Pat. No. 3,606,503 dated Sept. 20, 1971.

The present invention relates to improvements in swivel castor assemblies.

Some prior known rolling bearing assemblies of the type used for example in a swivel castor, consist of inner and outer bearing elements in the form of rings having confronting raceways or tracks which are spaced apart to accommodate a plurality of rolling elements for example, balls. Each ring has an associated support member and an opening is provided in one of the rings to permit assembly of the rolling elements between the rings. The opening may be sealed by a plug after the rolling elements have been inserted into the space between the raceways.

One of the disadvantages of this type of prior art arrangement is the fact that since the two bearing rings are formed integrally with the support members, the raceways have to be machined subsequently to obtain the accurate configuration which, of course, is necessary for proper arrangement of the rolling elements relative to the raceways. Furthermore, these assemblies are rather expensive to manufacture since these assemblies are made of cast or forged steel parts and require various operations for finishing such as turning the bearing raceways, tempering and grinding.

A further disadvantage in these assemblies, particularly when they are employed in swivel castors, is that when the bearing is subjected to lead from forces exerted by the rolling elements, it has been found that it is necessary to fill the access opening for assembling the rolling elements with a special plug member which is of the same material as the rings and has a smooth surface confronting the balls perfectly conforming to the rest of the raceway. This is a difficult and expensive assembly to make properly.

Still another disadvantage is that the forces effect an increase in stress on the material at the edge of the plug member and in the area of the access opening resulting in decreased life of the entire assembly.

Other known assemblies comprise essentially of confronting plate-like support members wherein the raceways are formed by a stamping operation. In this type of configuration, it is necessary to provide retaining means to hold the plate members relative to one another which usually consists of a centrally disposed pin, rivet or a ring member for holding the plate-like support members in place after the rolling elements have been positioned between the raceways. This is obviously a complex assembly.

An object of the invention is to provide a method for manufacturing a bearing construction of the aforesaid type, in accordance with which the bearing can be manufactured considerably cheaper but is of high quality.

Another object of the invention is to provide a rolling bearing construction which is not only simple and easy to manufacture, but also suitable for automatic mass production.

Still another object of the invention is to provide a rolling bearing construction in particular for a swivel castor in which a simple plug member can be used.

In accordance with the present invention, the inner and outer rings of the rolling bearing assembly are completely formed and thereafter secured to their respective support members by suitable means for example welding, soldering, glueing or other means. Preferably the rings are projection-welded to the support member and are tempered prior to assembly to their respective support members.

In the present instance the inner and outer rings are secured at opposite axial end faces to their respective support members and an access opening is formed in the inner ring which is aligned with an orifice in the support member to which the inner ring is attached whereby the rolling elements may be inserted through the aligned orifice and opening into the annular space between the rings.

Forming and machining of the rings can be done automatically. The plates can also be cut to their proper sizes and machined by an automatic process. Tempering of the rings and fixing them to the plates can be done automatically, while feeding the rolling elements through the access hole by assembling the bearing can also be done easily the automatic way.

It is noted that the greatest strain exerted on the rolling elements for example in a castor assembly of the type shown in the drawings is at two diametrically opposing areas of the bearing assembly, that is, in the plane determined by the traveling position of the castors and that these strains rapidly diminished to zero from the two diametrically opposed areas of greatest strain towards the area situated at from these points. Accordingly, the rolling elements of the bearing raceways situated at these areas are free of any strain. Thus, in accordance with the present invention, the access or feed opening for the rolling elements is located in the bearing element or ring which is connected to the support member on which the castor support is fixed or forms part of it and the axis of the opening is oriented so that it is perpendicular to the direction of the movement of the castor. In this way the area adjacent the access opening is not loaded so that a relatively simple stopper closing the access opening may be used since its only function is to prevent the rolling elements from escaping. Preferably, the plug member or stop is formed from a plastic material and snap fitted into the access opening.

In a preferred embodiment of the invention the access hole is formed in the inner bearing element while the associate support member has been provided with an orifice, allowing a tube-like tool to be inserted into the access hole from the outside, to feed the rolling elements into the space in between the bearing tracks by assembling the rolling bearing. In this embodiment the stopper can conveniently be formed so that it simultaneously blocks said orifice so as a perfect stopping is achieved.

Referring now to the drawing and particularly to FIG. 1 thereof, the bearing assembly of the present invention consists of a pair of rings, an inner ring 1 and an outer ring 2 which are secured, for example, by welding to plate members 3 and 4 respectively at opposite axial end faces of the inner and outer rings. The rings 1 and 2 are made of steel and formed with circumferentially extending grooves defining raceways 5 and 6 formed in such a manner that the rolling elements, in the present instance balls 7 bear or ride on the raceways at four points.

In order to assemble the balls 7 in the annular space between the rings, an access opening 8 is formed in the inner axial wall of the inner ring 1 and an orifice 9 is provided in the plate member 3 to the side of and adjacent the access opening 8. This arrangement with the rings properly positioned relative to one another, the balls 7 can simply be fed through the orifice 9 and access opening 8 by a tube-like tool. After the balls have been assembled, the access opening 8 and orifice 9 may be closed by a stop member 10 which can be provided with a grease channel and a grease nipple 11 for lubricating the bearing.

There is illustrated in FIGS. 2 and 3 a swivel castor incorporating a bearing assembly in accordance with the present invention. The swivel castor comprises a castor 12 rotatably supported between the ears 13 of a U-shaped bracket wherein the upper cross plate 14 in the present instance forms the lower plate-like support member for the bearing assembly. It is noted that the bearing assembly shown in FIG. 1 may include its own lower plate 3 and that this plate may be suitably secured to the upper cross plate 14 of the castor assembly.

FIG. 3 illustrates how the action of the load P and impact load P, resulting from a load exerted in a vertical plane through the castor effects a resulting force R exerting a couple on the bearing whereby the balls and the raceways are peak loaded at two diametrically opposing areas. These areas are generally in the vicinity of the arrows marked A and A in FIG. 3. The areas of the bearing raceways situated 90 from the areas defined above are free of any strain and the access opening 8 is formed in the inner ring in the unloaded area of the raceway. Accordingly, no force will be exerted on the plug member 10 and this member will simply serve to prevent the balls from rolling to the outside through the orifice 8. It is noted that the relationship of the access opening 8 to loaded areas of the raceways remains the same even when the castor 12 rotates.

' In the embodiment shown the stopper 10 is formed to simultaneously block access opening 8 and orifice 9 and is made of a plastic material to be snap-fitted in place in the manner shown. Thus the stopper 10 has a pilot portion 10a engageable in the access opening and a main body portion 10b with a circumferential groove 10c to snap over the edge of the orifice 9, the pilot portion 10a having an arcuate face 10d to conform to the raceway of the inner ring.

The ball bearing according to the present invention consists of comparatively few parts which are of simple design whereby the assembly is relatively economical to manufacture.

WE CLAIM:

1. A swivel castor assembly comprising a bracket, a castor rotatably mounted on the bracket, a plate member for securing the castor assembly to a structure, a bearing assembly between said plate member and bracket to facilitate rotational movement of said bracket relative to said plate member, said bearing assembly comprising a pair of rings having confronting circumferentially extending raceways and spaced apart to define an annular space between said raceways, a plurality of rolling elements m the annular space engaging said raceways, one of said rings secured to said bracket and the other ring secured to said plate member, means defining an access opening in said one ring to permit assembly of said rolling elements, a plug for said access opening to retain the rolling elements, the rotational axis of said castor being offset relative to the central axis of said one ring whereby upon application of load to the castor the resulting force exerts a couple on the bearing assembly thereby peak loading the same in diametrically opposing areas and minimally loading the diametrically opposed zones between said areas, said access opening extending perpendicularly to a plane in which said load couple is active and disposed in one of said diametrically opposed zones of least load.

2. A swivel castor assembly as claimed in claim 1 including an orifice in said plate member in said bracket to facilitate assembly of the rolling elements through said orifice and access opening.

3. A swivel castor assembly as claimed in claim 2 wherein said plug member is of a configuration to simultaneously seal said orifice and access opening. 

1. A swivel castor assembly comprising a bracket, a castor rotatably mounted on the bracket, a plate member for securing the castor assembly to a structure, a bearing assembly between said plate member and bracket to facilitate rotational movement of said bracket relative to said plate member, said bearing assembly comprising a pair of rings having confronting circumferentially extending raceways and spaced apart to define an annular space between said raceways, a plurality of rolling elements in the annular space engaging said raceways, one of said rings secured to said bracket and the other ring secured to said plate member, means defining an access opening in said one ring to permit assembly of said rolling elements, a plug for said access opening to retain the rolling elements, the rotational axis of said castor being offset relative to the central axis of said one ring whereby upon application of load to the castor the resulting force exerts a couple on the bearing assembly thereby peak loading the same in diametrically opposing aReas and minimally loading the diametrically opposed zones between said areas, said access opening extending perpendicularly to a plane in which said load couple is active and disposed in one of said diametrically opposed zones of least load.
 2. A swivel castor assembly as claimed in claim 5 including an orifice in said plate member in said bracket to facilitate assembly of the rolling elements through said orifice and access opening.
 3. A swivel castor assembly as claimed in claim 2 wherein said plug member is of a configuration to simultaneously seal said orifice and access opening. 